Production of alkyl aluminum compounds



p 21, 1965 K. ZIEGLER ETAL 3,207,774

PRODUCTION OF ALKYL ALUMINUM COMPOUNDS Filed April 19, 1962 UnitedStates Patent 3,207,774 PRODUCTION OF ALKYL ALUMINUM COMPOUNDS KarlZiegler, Kaiser-Wilhelm-Platz 1, Mulheim (Ruhr),

Germany, and Hans-Georg Geliert, Mulheim (Ruhr),

Germany; said Gellert assignor to said Ziegler Filed Apr. 19, 1962, Ser.No. 188,760 Claims priority, application Germany, Apr. 1, 1955, Z 4,843;May 25, 1955, Z 4,937 2 Claims. (Cl. 260-448) This invention relates tonew and useful improvements concerning the production of alkyl aluminumcompounds and is a continuation-in-part of our copending applicationSerial No. 573,470, filed March 23, 1956.

Aluminum dialkyl hydride and aluminum trialkyl compounds are valuableproducts for organic synthesis or other reactions and notably ascatalyst or catalyst components in the polymerization of olefins andespecially of ethylene in accordance with the Ziegler method. Thealuminum organic component, however, has been relatively difiicult andcostly to obtain. Though an improvement in this respect has beenachieved by the copending application U.S. Serial No. 484,576 concerningthe production of trialkyl aluminum compounds by the interaction ofaluminum olefins and hydrogen, the cost and other factors involved inthe practice of this method are still not sufiiciently favorable.

One object of the invention concerns the production of alkyl aluminumcompounds in a simplified manner.

This, and further objects of the invention will be seen from thefollowing description, one of the preferred embodiments of the inventionbeing illustrated in the accompanying fiow sheet.

In accordance with the invention, aluminum, aluminum trialkyl andhydrogen are reacted at a pressure in excess of 20 atmospheres and theresulting dialkyl aluminum hydride or its solution in aluminum trialkylmay be either separated as such or may be further treated with olefinsto yield aluminum trialkyl. It is thus possible, when using the two stepprocedure, to obtain from aluminum trialkyl in simple and effectivemanner further amounts of aluminum trialkyl.

When heating aluminum with an aluminum trialkyl and hydrogen underpressure an amount of hydrogen equivalent to the aluminum is absorbed bythe mixture and there is formed dialkyl aluminum hydride in accordancewith the following formula:

It is thus seen that by the addition of aluminum and hydrogen three molof alkyl aluminum are formed for every two aluminum trialkyl submittedto the reaction. The three mol of alkyl aluminum compound are present,as stated, in the form of dialkyl aluminum hydride which by the simpleexpedient of olefin addition can be converted into the trialkyl aluminumproduct or may be used as such. The dialkyl aluminum hydrides aregenerally considerably more stable against heat than aluminum hydrideitself which literally decomposes at temperatures below 100 G, intoaluminum and hydrogen.

The reaction of the aluminum with the aluminum trialkyl and hydrogen ispreferably carried out with aluminum in finely subdivided form. It isthus expedient to,

for instance, grind aluminum shot or particled aluminum prior or duringthe reaction or to use molten aluminum as the starting material forobtaining aluminum in finely subdivided form. By far the most effectivemethod for the conversion of the aluminum into a finely dispersed,highly reactive condition is the dispersion or atomization of moltenaluminum by way of an inert gas stream under pressure projecting orpropelling the molten alumi-. num directly into the liquid aluminumtrialkyl.

With the technical aids available today, such a method can be completelycontrolled and is readily executable despite the spontaneouscombustibility of the aluminum trialkyls such as particularly ofaluminum triethyl. It is, however, ordinarily preferred to avoid the useof concentrated pure aluminum trialkyl in the first stage of the method.For that reason, it is of advantage not to atomize or project the moltenaluminum directly into pure or highly concentrated aluminum trialkyl,but rather into an indifferent or inert solvent with respect to thealuminum trialkyl, the solvent to preferably already contain 3 to 10% ofdissolved aluminum trialkyl. Suitable solvents of this type are forinstance, saturated hydrocarbons of the aliphatic type such as hexane orhydrocarbons of the aromatic type such as benzene. The olefins which maybe used for the second reaction stage, if conversion to trialkylaluminum compounds is desired, cannot be used as such for solventpurposes in connection with the first reaction stage producing thedialkyl aluminum hydride products because such olefins will interferewith the production of the dialkyl aluminum hydrides. Further thesolvent should be preferably so selected that the same has anappreciable boiling point differential with respect to the aluminumtrialkyl and preferably a boiling point at least 50 C. higher or lowerthan that of the aluminum trialkyl.

When using the molten aluminum atomization method, it is desirable tocirculate the liquid into which the aluminum is projected at arelatively rapid rate. Using such circulatory system it is of advantageto project the aluminum into the liquid at a given point and so controlthe circulation that a settling of the atomized aluminum will occur atanother point within the cycle. It is then possible to obtain within theregion of such a settling zone a relatively viscous suspensioncontaining large amounts of aluminum. Thus for instance when circulatingin the atomization circulatory system a solution which contains, forexample, at the point of aluminum projection, about 5% by weight ofaluminum, a thick suspension of aluminum of up to 30% by weight may becontinuously withdrawn by way of a pressure pulp pump or similar device.This heavy suspension may then be further used.

In lieu of using atomized molten aluminum it is also possible to obtainan aluminum activated in a difierent manner, as for instance, analuminum activated as set forth in copending application U.S. Serial No.484,576 by mechanical comminution under avoidance of the formation of apassive oxide layer upon the active surface or which has been activatedby a chemical treatment with dialkyl aluminum monohalogenides.

The reaction between aluminum, aluminum trialkyl and hydrogen isadvantageously carried out at a temperature between and 200 C. andpreferably between and C. at pressures of at least 20 atmospheres andpreferably at least 60 atmospheres. The upper limit of the pressure isprimarily one of practical application determined by the structuralfeatures of the apparatus. In most cases however, a top pressure of 250atmospheres is applicable. Temperatures as low as 60 C. may be used and,as indicated in the examples, reaction periods of one half to twentyhours and more are applicable.

The liquid reaction product obtained in the first stage of the reactionmay then be worked up for the recovery, if desired, of dialkyl aluminumhydride or the same may be further treated for the production ofaluminum trialkyls utilizing olefins.

In this case it is possible, in accordance with one embodiment of theinvention, and preferably when using ethylene or monosubstitutedethylenes to effectuate the action of hydrogen upon the aluminum in thepresence of aluminum trialkyls and the olefin addition in separatestages. In that event the reaction of the olefins with the dialkylaluminum hydrides is effectuated under appreciably milder conditionsthan is the hydrogen absorption. The reaction temperature in theaddition or olefin reaction stage is advantageously from 50 to 80 C. andpreferably 60 to 65 C. By utilizing this means of operation it isavoided that olefin and hydrogen will come together in a single reactionmixture so that side reactions which may lead to saturated hydrocarbonscannot take place.

In accordance with another embodiment of the invention, the reactionproduct of the first reaction stage, i.e., the formation of dialkylaluminum hydrides, is directly treated with olefins. In this case,aluminum is first heated with aluminum trialkyls under hydrogen pressureand the olefin is then pressed in at temperatures of about 110 to 120 C.The pressure feeding of the olefin is advantageously carried out at sucha rate of speed that the olefin concentration within the reaction mix isat all times very low. Under these circumstances the reaction mix willcontain ordinarily during the reaction a certain amount of free dialkylaluminum hydride. It has been found desirable for smooth and expeditiousoperations, in accordance with the invention, to deliberately so adjustconditions that there is always present in the reaction mix some freedialkyl aluminum hydride. This is readily secured by adjusting orcontrolling the weight of addition of the olefin and may be easilysupervised or controlled by way of samples withdrawn and nitrogen andtesting the sample with isochinolin which, in the presence of dialkylaluminum hydride, causes the appearance of a red coloration. This testis very sensitive.

The reaction products obtained and still containing at least smallamounts of free dialkyl aluminum hydride may then be converted byadjustment of the olefin addition and pressure feeding of additionalhydrogen into pure dialkyl aluminum hydrides or by the addition ofincreased amounts of olefins into pure aluminum trialkyls.

The olefin pressure may vary within wide limits. Thus, for instance,when using ethylene it is readily possible to use atmospheric pressure.The important thing is that a certain interrelation exists between thetemperature which is preferably maintained during the olefinization andthe olefin pressure as well as the desired volumetime-yield whichoccurs. Ordinarily, again exemplifying the use of ethylene, the ethylenepressure does not need to exceed to 20 atmospheres and a temperature of50 to 80 C. usually sufiices. If, however, the temperature is increasedto about 90 to 100 C. the simple passage of ethylene through thereaction mix at normal pressure will be sufficient.

In commercial operations, the production of aluminum trialkyls inaccordance with the invention is most advantageously effected in arecycling procedure which is hereafter exemplified in connection withExample 6. Though it is there shown by way of a specific production ofaluminum triethyl, this procedure is equally applicable to other olefinsas is readily apparent. In the utilization of this recycling procedure,there are preferably used two pressure reaction towers which aresuitably combined.

In the first tower the reaction between aluminum, aluminum triethyl andhydrogen is effected. The liquid reaction product is then passed intothe second reaction tower of the pressure type in such manner that aslittle as possible, and preferably no hydrogen, passes into this secondtower. Portions of the metallic aluminum, however, may be passed intothe second reaction tower with out causing any difiiculty with respectto the therein contemplated olefin reaction. In this second tower thereaction mix is brought into contact with the olefin and in the specificcase with ethylene whereby the aluminum diethyl hydride is converted toaluminum triethyl, a considerable aluminum increase results. The newlyformed aluminum triethyl is then continuously withdrawn from the secondtower. It is of advantage to synchronize this withdrawal of the newlyformed aluminum trialkyl with the continuous aluminum feed in the firstreaction tower. In the practical operation of such a recyclingprocedure, and especially when utilizing substantially pulverized oratomized aluminum it is of advantage to carry in the cycle more liquidsbe it aluminum trialkyl or its solution in an indifferent solvent, thanis ultimately necessary for the subsequent reaction of the aluminumitself. It is for that reason, in such a recycling procedure preferredto first feed the entire amount of liquid which exits from the secondreaction tower into the cycle for the production of the atomizedaluminum and to then withdraw at a suitable point, from this lastmentioned cycle, the continuously formed aluminum triethyl. The metallicaluminum is recycled into the first reaction tower by way of a pumpsuitable for the feeding of pulpy materials. A second pump presses somuch pure aluminum triethyl into the first tower as is necessary for theobtaining of a smooth reaction.

If operations are conducted in the presence of solvents, the reactionproduct from the second reaction tower is separated by distillation intosolvent and aluminum triethyl. The solvent is then again provided with afew percent of aluminum triethyl. Alternatively it is possible, bysuitable adjustment of the distillation, to obtain a solvent containingthe desired or required amount of aluminum triethyl concentration. Thesolution of the aluminum triethyl is then recycled into the atomizationcycle. The triethyl exiting from the second reaction tower may bepartially passed into the first reaction tower by way of a suitable feedpump.

The invention offers the following practical and technical advantages:

In previously proposed methods for the production of dialkyl aluminumhydrides it was only possible to obtain dialkyl aluminum hydrides of thetype of aluminum diisobutylhydride with relative ease of theirproduction because these materials may be more or less readily obtainedfrom compounds of the type of aluminum triisobutyl by the directsplitting off of isobutylene while heating. In accordance with theinvention, however, it is possible to also obtain very readily dialkylaluminum hydrides if the same carry in alpha position non-branched andespecially primary aliphatic constituents.

Furthermore, the procedure, in accordance with the invention,constitutes an appreciable advance in the production of certain aluminumtrialkyls. The previously proposed preparation of aluminum trialkylsfrom aluminum, hydrogen and olefins, will only proceed relativelysmoothly with branch-chain hydrocarbons of the type of isobutylene. Whenusing ethylene and singly substituted ethylenes, difiiculties areexperienced in the practice of the method because the same must becarried out under conditions at which ethylene and singly substitutedethylenes will further react with the aluminum trialkyls which haveformed as reaction products.

In the production of the aluminum trialkyls, in accordance with theinvention, it is of advantage to make use of the following:

Since at the beginning of the reaction, in accordance with the inventionthere are present at least two molecules of aluminum trialkyl for eachgram-atom aluminum metal and since after the addition of the olefin tothe resulting reaction products, there are returned three molecules ofaluminum trialkyl, it is possible to produce, by a repetition of thereaction sequence, any desired amounts of aluminum trialkyl from anyspecific starting amount of such materials.

Thus, by proceeding in this manner, it is possible to obtain simply andsmoothly trialkyl aluminum compounds by a reaction which, once started,basically involves the use of aluminum, olefine and hydrogen. Thus, fromaluminum, propylene and hydrogen, aluminum tripropyl is very readily,smoothly and economically obtained, the propylene being added underpressure in liquid form. In an analogous manner there may be obtainedfrom aluminum, ethylene and hydrogen, with excellent yields, aluminumtriethyl. Also other alpha olefins may be used in a similar manneryielding, in accordance with the invention, high amounts of aluminumtrialkyls. The number of carbon atoms, as to any alkyl which is to beadded to the aluminum to constitute a trialkyl compound to be made inaccordance with the invention, is not critical and as high as 20 carbonatoms are readily obtainable by way of the alkyl radicals attached tothe aluminum.

Example 1 90 grams of aluminum shot grams equivalents) are wet-groundwith 6 mol (:684 g.) aluminum triethyl for 24 hours in a ball millfilled with nitrogen. The resulting suspension is thereafter passed intoa 2 liter autoclave filled with nitrogen and thereafter about 250atmospheres of hydrogen are pressed in. While heating to a temperatureof about 100 to 110 C., while shaking or rotating the autoclave, thepressure reduces within a period of about 3 to 4 hours down to about 80atmospheres. If the hydrogen pressure does not further reduce, theautoclave is permitted to cool and the hydrogen is depressurized.Thereupon the liquid contents of the autoclave are withdrawn undernitrogen. The reaction mass is of a dark coloration because ofimpurities of the aluminum used and because of small amounts ofunreacted aluminum. The reaction product may be easily freed from theseimpurities by distillation, centrifuging or filtration. Upondistillation in high vacuum there are obtained 700 grams of almost purediethyl aluminum hydride (boiling point 45-50 C. at 10* mm. Hg) whichcontains only little aluminum triethyl.

Example 2 Molten aluminum, running out of a nozzle, is first atomizedwith a blast of an indifferent gas such as nitrogen, the atomized spraybeing propelled or projected into aluminum tripropyl to thereby obtain asuspension of finely dispersed aluminum with a highly active surface.This suspension is adjusted to an aluminum content of about 10% byweight by removal of a portion of the aluminum tripropyl. 100 grams ofthe 10% aluminum suspension are then passed into a nitrogen filledautoclave of 500 cc. content. Thereafter hydrogen is pressed into theautoclave at a pressure of 60 atmospheres whereupon the autoclave isheated to a temperature of l25-l30 C. while the same is shaken orrolled. The pressure will reduce within a period of 6 to 7 hours down toabout 30 atmospheres. After cooling the hydrogen is depressurized. Theliquid reaction product is thereafter withdrawn under suitableprecautions, such as under nitrogen, from the autoclave, is thereafterfirst freed in vacuum from the dissolved hydrogen and is finallydistilled in a high vacuum. There are obtained about 100 grams ofpractically pure dipropyl aluminum hydride constituting a substantiallycolorless self-igniting liquid.

Example 3 A suspension of 30 grams finely dispersed aluminum in 1070grams of aluminum tridodecyl are prepared in the manner set forth inExamples 1 or 2 whereupon a suspension is passed into an autoclave of 2liter content and filled with nitrogen. About atmospheres hydrogen arepressed in and the autoclave is heated to about ll01l5 C. while beingshaken or rolled. Within several hours the hydrogen pressure is reducedto about 40 atmospheres. If no further pressure reduction occurs, onepermits cooling to about 50 C., whereupon the hydrogen is depressurizedand the liquid contents, having a temperature of about 40 to 50 C. arepermitted to pass out of the autoclave. The impurities resulting fromthe original aluminum used and also from remnants of unreacted aluminumare filtered (always under nitrogen) while the reaction mix is stirredwarm and there is thus obtained in the filtrate a liquid whichsubstantially solidifies upon cooling to about 1020 C. and which, uponheating, again melts between about 35 and 40 C. This material shows onanalysis 7.3% aluminum (calculated for (C H AlH=7.4% Al). Upondecomposition with water, the material liberates per 0.366 (:1 millimol)the correct amount of 22.4 ccm. hydrogen.

Example 4 A suspension of 30 grams finely dispersed aluminum in otherthan 50 grams of aluminum trimethyl is obtained similar to the mannerdescribed in Examples 1 or 2 and the resulting suspension is thereafterpassed into an autoclave of 500 ccm. contents and filled with nitrogen.After the pressing in of 250 atmospheres of hydrogen, the autoclave isheated to about to C. while shaking or rolling the same. Within a fewhours the pressure reduces to about 120 atmospheres. Upon the completionof the reaction, which may be seen from the fact that the hydrogenpressure does not further reduce, one permits cooling to about 50 C.whereupon the hydrogen is depressurized, Thereafter the, at about 50 0.,still relatively thinly liquid dimethyl aluminum hydride is permitted toflow oif and the nitrogen thins. At room temperature the reactionproduct constitutes a very viscous liquid which may be separated fromimpurities by distillation in vacuo (boiling point 60-6l C. at 16 mm.Hg); there are obtained about 165 grams dimethyl aluminum hydride.

Example 5 A suspension of about grams aluminum in about 2 kilograms ofaluminum triisobutyl prepared in the manner set forth in Examples 1 or 2whereupon the suspension is passed into a 5 liter autoclave filled withnitrogen. Reaction is effected at a temperature of about 110 to 115 C.with hydrogen and 100 atmospheres pressure. After about five to sixhours, the hydrogen pressure reduces to about 20 atmospheres. Thehydrogen is now depressurized and the liquid reaction product is flashedoff and the nitrogen from the autoclave and upon removal of stillundissolved hydrogen the resulting product is distilled in a high vacuum(boiling point 105 C./2.l0* mm. Hg). There are obtained about 2.1 kg. ofpure diisobutyl aluminum hydride.

Example 6 In this example a continuous commercial method is illustratedin conjunction with the accompanying flow sheet:

The molten aluminum is atomized from the storage tank 1 into tank 2 inwhich there is a solvent which is passed into the same through theconduits 3 and 4. The solvent passed through conduit 3 contains a smallamount, such as 5%, aluminum triethyl. The mixture of finely atomizedaluminum and solvent layers in the setting tank or zone 5 into a fixedsuspension containing up to about 30% by weight of aluminum and analmost pure solvent which may be recycled by way of the pump 6 andconduit 4 into the atomizing tank 2. The aluminum suspension is thenpassed by way of the pulp type pump 7 into the lower portion of tower 1by way of the conduit 8. Hydrogen is passed into the reaction tower 1 byWay of the conduit 9 and so much aluminum triethyl is passed into thereaction tower 1 by way of pump 10 and conduit 11 as is required foreffecting of a desired reaction in tower 1. The reaction product intower 1 then passes through conduit 12 into a separator 13 in which thebalance of hydrogen is removed through conduit 14, the same being thenpassed through conduit 9 for reentry into the cycle. The diethylaluminum hydride passes through conduit 15 into the lower portion of thereaction tower II in which simultaneously ethylene was introduced by Wayof conduit 16. The reaction product of tower 11 then passes by way ofcondiut 17 into a distillation col-. umn 18 in which the product isseparated into unreacted ethylene solvent and aluminum triethyl. Theunreacted ethylene may be drawn off by way of the conduit 19 and may bepassed back into the cycle. The solvent may be returned by way ofconduit 3 through the atomizing tank of zone 2. The principal portion ofthe aluminum triethyl is drawn off by way of conduit 20 while anappropriate portion is passed back into the reaction tower 1 by way ofconduit 21, pump 10 and conduit 11. It is also possible to so adjust acontrol of the distillation in the distillation column that the solventwhich is removed by way of the conduit 3 already contains that amount ofaluminum triethyl which is desired for the aluminum triethyl content ofsolvent in the atomization tank or vessel 2. It is, however, alsopossible to withdraw substantially pure solvent and to thereafter addthe desired amount of aluminum triethyl.

The solvents that may be used are, for instance, hexane or benzene.However, any other solvents may be employed in the practice of this orthe other examples herein set forth utilizing solvents provided thesolvent is a solvent for the particular trialkyl aluminum utilized inthe process and is, at the same time, substantially indifferent or inertwith respect to the particular trialkyl aluminum compound, i.e., willnot cause the decomposition thereof.

Example 7 800 grams of aluminum shot are ground under nitrogen in a ballmill together with two liters of a 10% solution of aluminum tripropyland hexene for 12 hours, whereupon the resulting very uniform andreadily flowing suspension was transferred under nitrogen into a 13liter roller autoclave. The metallic aluminum was first permitted tosettle in the autoclave whereupon the predominant portion of the liquidsuspension agent was removed by suction. A further 400 grams of aluminumwere then ground with the removed suspension agent in the same ball millunder similar conditions in order to obtain further amounts ofsuspension which are then passed into the same autoclave so that thesame contains 1200 grams of aluminum finely suspended in about twoliters of the suspension agent. For a still better utilization of theautoclave content, the aluminum is again permitted to settle and onehalf of the liquid suspension agent is drawn off and a further 200 com.of aluminum tripropyl there added. Hydrogen was then fed in underpressure at 200 atmospheres at room temperature whereupon the autoclavewas heated to a temperature of 110 to 120 C. while the autoclave wasbeing rotated. The pressure in the autoclave amounted to 240atmospheres. After the temperature of 110 to 120 C. was reached, themotion of the autoclave was arrested and, by way of a pressure pump, 300grams liquid propylene were pressed into the autoclave and the same wasthereafter again placed into rotation. The temperature will temporarilyreduce somewhat. The temperature reduction is compensated by againbringing the same to 110 to 120 C. and heating is continued for minuteswith continuous rotation of the autoclave. Thereupon the addition ofliquid propylene under pressure is repeated in the manner abovedescribed. About commencing with the second or third propylene addition,a temporary increase and then decrease of the pressure down to theoriginal pressure value is observed. At this point, it is possible tocommence with the addition of the next following propylene portion. Thetotal pressure in the autoclave will not appreciably reduce althoughhydrogen is being consumed because the free gas volume within theautoclave becomes continuously smaller by reason of the increase of theliquid contents. The pressure increase and decrease is solely caused bypressure feeding of the propylene and the consumption of the propyleneby the reaction. The reaction may be continued up to practically thecomplete consumption of the aluminum. Only then will a further pressuredecrease not occur even with the pressure feeding of additionalpropylene. Thereafter the autoclave is permitted to cool and the same isemptied under nitrogen and the liquid reaction product is freed from thestill undissolved propylene and small amounts of a few percent ofdimerpropene and of hexane. The distillation in vacuo will then yield acompletely uniform and pure aluminum tripropyl having a boiling point of64/ 0.2 mm. in amount of 6.5-7 kg. With the complete dissolution of thealuminum, at the most 7 kilograms could be formed. The final reactionproduct, of course, also still obtains the initially added aluminumtripropyl to an extent of about 250 grams so that in the course of thepresent example the actually newly formed amount of aluminum tripropylis about 6.5 to 6.75 kilogram aluminum tripropyl.

From this example it may be seen that in accordance with the inventionadditional reactants may be fed in during the reaction to maintain thereaction conditions.

Example 8 Two liters of a hydrocarbon mixture derived from the crackingin accordance with Fischer-Tropsch-Gatsch and having a boiling range of165-220 C. with an alpha olefin content of 3 mol per liter are admixedwith 350 grams of aluminum triisobutyl and so much benzene that theboiling point of the mixture is -115 C. The mixture is then boiled underreflux and the amount of liberated isobutylene is measured. Afterseveral hours the correct amount of 250-280 grams of isobutylene hasbeen liberated and the alpha olefins have been converted into thecorresponding aluminum trialkyl mixtures which will also containadditionally the paraffin portion of the original cracking products aswell as the non-alpha olefins and a remainder of the excess of theoriginally present alpha olefins. There is then added 4 liters ofair-free and dry hexane and the mixture is filled under nitrogen into aball mill together with 2 kilograms of aluminum shot. The grinding iscarried out as described in Example 7 for 12 hours and there is thuslyobtained a uniformly flowing suspension of aluminum in a solution ofhigher aluminum trialkyls in hexane. The entire mixture is passed into asubstantially vertically arranged reactor of the pressure type of about15 centimeters inner diameter and about 4 meters high. The reactor isprovided with means permitting the pumping in of liquid crackinghydrocarbons as well as of pulpy aluminum suspension with the aid of apulp type pump and further permits the withdrawal of samples. Theautoclave is filled with hydrogen under 100 atmospheres pressure and thehydrogen is then circulated with the aid of a circulating pump in suchmanner that the same will enter the reactor at the lower portion andwill stir up the aluminum being then again passed out of the upper end.The reactor is first heated for about one half hour to a temperature ofabout C. whereupon liquid cracked olefins are pressed into the same withthe aid of an injection pump, these olefins being the same or of thesame type initially admitted to the reactor. Under the conditionsstated, the reacting olefin, as can be readily calculated, will absorbless hydrogen than corresponds to the volume of the pressed in liquidolefin so that the pressure will not reduce during the continuance ofthe reaction in the apparatus but will rather increase. It is in suchcases necessary to provide, in the event the pressure increase becomestoo high, for a depressurization of a portion of the hydrogen in asuitable storage tank.

In the particular arrangement described in this example, it is notreadily possible to observe the initiation and continuance of thereaction by way of pressure changes. It is, nevertheless, however,easily feasible to control and supervise the reaction by withdrawing,under nitrogen, small amounts of samples and to test the same withisochinolin. The olefin addition is then so regulated that the sampleswill always assume a distinctly yellow coloration upon the addition ofisochinolin. It will be observed that some time after an olefinaddition, the color of a sample will be more intense and there is thenalways added so much olefin that the color Will almost, but not quite,dis appear. The aluminum present in the reactor is completely sufiicientto convert a complete reactor charge of the starting olefins intoaluminum trialkyl.

If so much of the cracked olefins have been added to the reactor underpressure that the reactor is practically filled, the circulatory pumpfor the pressure hydrogen is then set still-always maintaining thereaction temperature-whereupon the reaction mixture is permitted toremain quiescent in the reactor for a short period of time so that thealuminum residues have a chance to settle whereupon most of the liquidreactor contents are withdrawn under depressurization into a tank orother container filled with nitrogen. The liquid reaction productobtained in this manner contains, per liter, about 25 to 30 grams ofbound aluminum. A portion of this reaction product is used for theproduction of a new aluminum suspension in the ball mill or liquidaluminum is atomized as described in Example 6 with the device there setforth into the reaction product in such manner that an approximately 10%aluminum containing readily flowable liquid and readily pumpablesuspension is obtained. This suspension is then passed into the reactorby way of a pulp type pump, the temperature of reaction having beensubstantially maintained in that reactor, there being restarted at thesame time the hydrogen cycle and the pump feeding of the olefin. It willbe readily seen that when pump feeding is 10% aluminum suspension and acontent in the reaction product of 2.5% of dissolved aluminum,approximately 4 times of the amount of the pump fed suspension volume ofolefin can be added. It is then possible very soon, whenever the reactoris again filled with reaction products, to continuously withdraw liquidreaction product at the upper end, advantageously by way of a built-inpressure filtration arrangement designed for retaining of aluminum. Inthis manner the entire process may be maintained as a continuousoperation by continuously diverting a portion of the liquid reactionproduct in order to produce new aluminum suspension.

Example 9 2 kilogram aluminum shot are charged into a 13 liter rollertype autoclave whereupon the autoclave was filled with nitrogen andthereafter for the wetting of the aluminum there being added a justsufficient amount of about 200 ccm. of ethyl aluminum sesquibromidewhich may be readily obtained by dissolving aluminum shot in ethylbromide. Thereafter there is at first carefully pressure fed into theautoclave 200 ccm. of liquid ethyl chloride and the autoclave, whileobserving its inside temperature is then rotated without applyingexternal heat. After some time the aluminum reacts with the ethylchloride Which is observable by a temperature increase. If thetemperature has again come down, two further portions of 200 grams eachof ethyl chloride are added and in each case the end of the reaction isawaited. By then a certain amount of surface reacted, or surfaceactivated, aluminum as well as a certain amount of sesquibromidecontaining ethyl aluminum sesquichloride has formed which is, as far aspossible, removed from the autoclave. Thereafter about 500 grams ofaluminum triethyl are added and hydrogen is pressure fed similar to theprocedure described in Example 7, the hydrogen being pressed in at apressure of 200 atmospheres whereupon heating is effected to atemperature of about 110120 C. After heating for about one half hourthere is at first a small amount of approximately 50 to 100 grams ofethylene admitted into the autoclave from a tank charged with highpressure ethylene whereupon rotation is continued for approximatelyanother 20 minutes, the procedure being thereafter repeated with respectto alternating rotation of the autoclave while heating the same and theaddition of ethylene whereby the amount of the individual ethyleneadditions may be increased commensurate with the progress of thereaction. Perhaps at the end of the procedure it is of advantage topressure feed once more hydrogen into the autoclave. If a suflicientamount of ethylene has been added as will correspond to the formation ofabout 10 liters, i.e., 8 kilograms of liquid aluminum triethyl, it is ofadvantage to interrupt the process in order to avoid the very dangersinherent in the overcharging of a pressure vessel. Thereafter theautoclave is permitted to cool and the same is depressurized, whereuponthe autoclave contents are withdrawn under nitrogen. Upon distillationin vacuo about 8 kilograms of aluminum triethyl corresponding to thefed-in ethylene are obtained. This aluminum triethyl contains smallamounts of diethyl aluminum halogenide derived from the originalactivation of the aluminum. For many uses of the aluminum triethyl suchhalogen content is not detrimental.

It will be noted that in the above Example 6 an illustration isfurnished of a general flow arrangement for continuous operations inaccordance with one of the preferred embodiments of the invention.Inasmuch, however, as this arrangement is applicable to the reactionconditions generally applying for the first trialkyl conversion andsecond olefin addition reaction, regardless of whether the same arecarried out as continuous or batch operations, specific values oftemperatures and pressures have not been included in Example 6, it beingunderstood that any of the conditions applying within the scope of thisinvention, and specifically those set forth in connection with thevarious other examples herein furnished, necessarily apply to thecontinuous operations of Example 6.

Wherever mention herein is made in connection with a finely sub-dividedaluminum as offering or having an active surface, or where such similardesignation is used, it is intended to cover thereby, as is wellunderstood, a reactive aluminum surface of the type set forth herein,as, for example, obtained by solvent grinding or by other mechanicalcomminution of aluminum under the conditions herein set forth andincluding activation with such activating agents as dialkylmonohalogenides. Such designation is also intended to include thepreferred embodiment of sub-divided aluminum obtained by atomization ofmolten aluminum into an organic solvent. It is in all cases understoodthat the organic solvents, wherever used in connection with theobtaining of a finely sub-divided aluminum having or offering an activesurface are such as will be inert with respect to aluminum and in theirspecific application to the present invention will be solvents for thealuminum trialkyl used in the invention and will be inert with respectthereto.

We claim:

1. A process for the manufacture of triethylaluminum comprising formingan essentially halogen-free charge comprising comminuted solid aluminumand liquid triethylaluminum, the aluminum being in substantial excess ofthe triethylaluminum, then contacting said charge with ethylene andhydrogen at a superatmospheric partial pressure and a total pressure offrom 10-150 atmospheres and maintaining said system at a temperature of-130 C. for a reaction period of at least 0.5 hours and feedingadditional ethylene during said period to maintain superatmosphericpartial pressure and a total pressure within said range.

2. A process for the manufacture of triethylaluminum 11 12 comprisingforming an essentially halogen-free charge References Cited by theExaminer comprising cornminuted solid aluminum and liquid tri- UNITEDSTATES PATENTS ethylaluminum, the aluminum being in substantial excessof the triethylaluminum, then contacting said charge with 2,886,581 5/59Redman 260-448 ethylene and hydrogen at a superatmospheric partial pres-5 FO PATENTS if f R3 of 5 i 10450 gg z gfi 836,792 6/60 Great Britain.

an mam aimng sar sys em a a empera ure 0 201,610 1/59 Austria.

C. for a reaction period of at least 0.5 hour and feeding additonalreactant during said period to maintain super- TOBIAS LEVOW PrimaryExaminer atmospheric partial pressure and a total pressure within 10said range ABRAHAM H. WINKELSTEIN, Examzner.

2. A PROCESS FOR MANUFACTURE OF TRIETHYLALUMINUM COMPRISING FORMING ANESSENTIALLY HALOGEN-FREE CHARGE COMPRISING COMMINUTED SOLID ALUMINUM ANDLIQUID TRIETHYLALUMINUM, THE ALUMINUM BEING IN SUBSTANTIAL EXCESS OF THETRIETHYLALUMINUM, THEN CONTACTING SAID CHARGE WITH ETHYLENE AND HYDROGENAT A SUPERATMOSPHERIC PARTIAL PRESSURE AND A TOTAL PRESSURE OF FROM10-150 ATMOSPHERES